import os
import mimetypes
from typing import Tuple
from fastapi import UploadFile, HTTPException
from config import settings


def validate_file(file: UploadFile) -> Tuple[bool, str]:
    """
    验证上传的文件
    
    Args:
        file: FastAPI上传文件对象
        
    Returns:
        (是否通过验证, 错误信息)
    """
    # 检查文件名
    if not file.filename:
        return False, "文件名不能为空"
    
    # 检查文件大小
    if hasattr(file, 'size') and file.size > 1024 * 1024 * 1024:  # 1GB = 1024^3 bytes
        return False, f"文件大小超过限制 (1GB)"
    
    
    # 检查文件扩展名
    _, ext = os.path.splitext(file.filename.lower())
    if ext not in [e.lower() for e in settings.allowed_extensions]:
        return False, f"不支持的文件类型。支持的类型: {', '.join(settings.allowed_extensions)}"
    
    return True, ""


def get_content_type(filename: str) -> str:
    """
    根据文件名获取MIME类型
    
    Args:
        filename: 文件名
        
    Returns:
        MIME类型字符串
    """
    content_type, _ = mimetypes.guess_type(filename)
    return content_type or "application/octet-stream"


def format_file_size(size_bytes: int) -> str:
    """
    格式化文件大小
    
    Args:
        size_bytes: 文件大小（字节）
        
    Returns:
        格式化后的文件大小字符串
    """
    if size_bytes == 0:
        return "0B"
    
    size_names = ["B", "KB", "MB", "GB", "TB"]
    i = 0
    size = float(size_bytes)
    
    while size >= 1024.0 and i < len(size_names) - 1:
        size /= 1024.0
        i += 1
    
    return f"{size:.2f}{size_names[i]}"


def extract_object_key_from_url(file_url: str) -> str:
    """
    从文件URL中提取对象键
    
    Args:
        file_url: 文件URL
        
    Returns:
        对象键
    """
    # 假设URL格式为: https://bucket.endpoint.com/object_key
    try:
        return file_url.split('/')[-1]
    except:
        return ""


def sanitize_filename(filename: str) -> str:
    """
    清理文件名，移除特殊字符
    
    Args:
        filename: 原始文件名
        
    Returns:
        清理后的文件名
    """
    # 移除或替换特殊字符
    invalid_chars = '<>:"/\\|?*'
    for char in invalid_chars:
        filename = filename.replace(char, '_')
    
    return filename.strip()